January 1992
Volume 33, Issue 1
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Articles  |   January 1992
Stromal acidosis affects corneal hydration control.
Author Affiliations
  • S R Cohen
    Morton D. Sarver Laboratory for Cornea and Contact Lens Research, School of Optometry, University of California, Berkeley.
  • K A Polse
    Morton D. Sarver Laboratory for Cornea and Contact Lens Research, School of Optometry, University of California, Berkeley.
  • R J Brand
    Morton D. Sarver Laboratory for Cornea and Contact Lens Research, School of Optometry, University of California, Berkeley.
  • J A Bonanno
    Morton D. Sarver Laboratory for Cornea and Contact Lens Research, School of Optometry, University of California, Berkeley.
Investigative Ophthalmology & Visual Science January 1992, Vol.33, 134-142. doi:
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      S R Cohen, K A Polse, R J Brand, J A Bonanno; Stromal acidosis affects corneal hydration control.. Invest. Ophthalmol. Vis. Sci. 1992;33(1):134-142.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

An estimate of overall corneal hydration control can be obtained by measuring the rate of thickness recovery following induced corneal swelling; it is expressed as the percent recovery per hour (PRPH). This recovery is nearly, but not exactly, exponential, because there appears to be an initial slower recovery phase lasting about 30-40 minutes. This 30-40 minute period of slower recovery corresponds to the time when corneal pH is reduced secondary to the contact lens-induced swelling, suggesting the possibility that stromal acidosis may retard the corneal deswelling process. In this study, we explored the effects of corneal acidosis on hydration control by monitoring corneal recovery under normal and reduced pH conditions. Corneal pH was controlled by having subjects were goggles and exposing their eyes to air (normal pH) or a gas mixture providing 21% O2 and 7% CO2 (low pH). Relative corneal pH levels were monitored by measuring fluorescence intensity (FI) ratios, which showed that the average (+/- standard deviation) FI ratio was significantly lower under 7% CO2 (0.838 +/- .024) vs air (0.985 +/- .025; P = 0.0001), corresponding to approximate pH values of 7.25 vs 7.50. Under these reduced pH conditions, open-eye steady-state (OESS) corneal thickness was not substantially affected. For 10 subjects, mean (+/- SD) corneal thickness decreased 0.93 +/- 3.7 microns vs 1.10 +/- 4.50 microns after exposures to 60 minutes of 7% CO2 and 40 minutes of air (P greater than or equal to 0.45), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

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